linux-kernel - [PATCH 08/10] blk-cgroup: remove radix_tree

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Message-Id: <20250925081525.700639-9-yukuai1@huaweicloud.com>
Date: Thu, 25 Sep 2025 16:15:23 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: tj@...nel.org,
	ming.lei@...hat.com,
	nilay@...ux.ibm.com,
	hch@....de,
	josef@...icpanda.com,
	axboe@...nel.dk,
	akpm@...ux-foundation.org,
	vgoyal@...hat.com
Cc: cgroups@...r.kernel.org,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	yukuai3@...wei.com,
	yukuai1@...weicloud.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	johnny.chenyi@...wei.com
Subject: [PATCH 08/10] blk-cgroup: remove radix_tree_preload()

From: Yu Kuai <yukuai3@...wei.com>

Now that blkcg_mutex is used to protect blkgs, memory allocation no
longer need to be non-blocking, this is not needed.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 block/blk-cgroup.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 280f29a713b6..bfc74cfebd3e 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -893,16 +893,10 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 			goto fail_unlock;
 		}
 
-		if (radix_tree_preload(GFP_KERNEL)) {
-			blkg_free(new_blkg);
-			ret = -ENOMEM;
-			goto fail_unlock;
-		}
-
 		if (!blkcg_policy_enabled(q, pol)) {
 			blkg_free(new_blkg);
 			ret = -EOPNOTSUPP;
-			goto fail_preloaded;
+			goto fail_unlock;
 		}
 
 		blkg = blkg_lookup(pos, q);
@@ -912,12 +906,10 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 			blkg = blkg_create(pos, disk, new_blkg);
 			if (IS_ERR(blkg)) {
 				ret = PTR_ERR(blkg);
-				goto fail_preloaded;
+				goto fail_unlock;
 			}
 		}
 
-		radix_tree_preload_end();
-
 		if (pos == blkcg)
 			goto success;
 	}
@@ -925,8 +917,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 	ctx->blkg = blkg;
 	return 0;
 
-fail_preloaded:
-	radix_tree_preload_end();
 fail_unlock:
 	mutex_unlock(&q->blkcg_mutex);
 	/*
@@ -1479,14 +1469,12 @@ int blkcg_init_disk(struct gendisk *disk)
 {
 	struct request_queue *q = disk->queue;
 	struct blkcg_gq *new_blkg, *blkg;
-	bool preloaded;
 
 	new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL);
 	if (!new_blkg)
 		return -ENOMEM;
 
 	mutex_lock(&q->blkcg_mutex);
-	preloaded = !radix_tree_preload(GFP_NOIO);
 
 	/* Make sure the root blkg exists. */
 	blkg = blkg_create(&blkcg_root, disk, new_blkg);
@@ -1494,16 +1482,12 @@ int blkcg_init_disk(struct gendisk *disk)
 		goto err_unlock;
 	q->root_blkg = blkg;
 
-	if (preloaded)
-		radix_tree_preload_end();
 	mutex_unlock(&q->blkcg_mutex);
 
 	return 0;
 
 err_unlock:
 	mutex_unlock(&q->blkcg_mutex);
-	if (preloaded)
-		radix_tree_preload_end();
 	return PTR_ERR(blkg);
 }
 
-- 
2.39.2